import numpy as np

def fun(x):
    return 3*x*x-np.exp(x)

def zf(x):
    if x>0:
        return '+'
    elif x<0:
        return '-'
    else:
        return '0'

def zf_for_lst(x_lst):
    return [zf(x) for x in x_lst]


x=np.arange(-7.5,7.5+0.1,0.5)
y=fun(x)
zf_lst=zf_for_lst(y)

print(x)
print(zf_lst)



